Revert of Don't expose --disable-gpu-compositing, only set internally. (https://codereview.chromium.org/300523002/)

Reason for revert:
Makes a bunch of virtual/softwarecompositing tests Timeout on Mac
https://code.google.com/p/chromium/issues/detail?id=377145

Original issue's description:
> Don't expose --disable-gpu-compositing, only set internally.
> 
> The flag isn't meant to be set externally, it doesn't work on most
> configs. It's only meant internally to make sure the renderer doesn't
> try to use GPU when the browser is in software.
> 
> BUG=None
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=272636

TBR=jbauman@chromium.org,piman@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=None

Review URL: https://codereview.chromium.org/299383002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@272707 0039d316-1c4b-4281-b951-d872f2087c98
3 files changed